1. Field of the Invention
The invention relates to a product information display device and a data transfer arrangement, in particular a modulated laser data transfer arrangement, for example for use in transferring data to a remote product status display device such as an LCD supermarket shelf tag.
2. Description of the Related Art
Recent developments in store price tagging technology have been directed towards improving the accuracy and consistency of price tagging of products, together with the visual attractiveness of tagging systems. One such development has been the LCD price tag. Such systems are well known to the skilled man and can be implemented without the need for detailed discussion here. As a brief summary, however, an LCD price tag system is shown in FIG. 1, generally referenced 100. An LCD price tag 102 includes an LCD display 104 and manual data input means such as a series of keys 106; the keys are preferably concealed to avoid tampering by customers. The LCD price tag 102 displays the price of the items 108 on a shelf 110 on which the price tag 102 is mounted. When it is desired to change the price of the items 108, this is a laborious task as the price tag 102 must be altered manually. It will be seen that where a number of prices have to be changed, the task becomes correspondingly more laborious and time consuming. In a modern sales environment where prices are changed very regularly it will be seen that considerable disadvantages are associated with the known system.
In another aspect, electro-optical readers, such as bar code symbol readers, are now quite common. Typically, a bar code symbol comprises one or more rows of light and dark regions, typically in the form of rectangles. The widths of the dark regions, i.e., the bars, and/or the widths of the light regions, i.e., the spaces, between the bars indicate encoded information to be read.
A bar code symbol reader illuminates the symbol and senses light reflected from the coded regions to detect the widths and spacings of the coded regions and derive the encoded information. Bar code reading type data input systems improve the efficiency and accuracy of data input for a wide variety of applications. The ease of data input in such systems facilitates more frequent and detailed data input, for example to provide efficient inventories, tracking of work in progress, etc. To achieve these advantages, however, users or employees must be willing to consistently use the readers. The readers therefore must be easy and convenient to operate.
A variety of scanning systems are known. One particularly advantageous type of reader is an optical scanner which scans a beam of light, such as a laser beam, across the symbols. Laser scanner systems and components of the type exemplified by U.S. Pat. Nos. 4,387,297 and 4,760,248--which are owned by the assignee of the instant invention and are incorporated by reference herein--have generally been designed to read indicia having parts of different light reflectivity, i.e., bar code symbols, particularly of the Universal Product Code (UPC) type, at a certain working range or reading distance from a hand-held or stationary scanner.
FIG. 2 illustrates an example of a prior art bar code symbol reader 10 implemented as a gun shaped device, having a pistol-grip type of handle 53. A lightweight plastic housing 55 contains a light source 46, a detector 58, optics 57, signal processing circuitry 63, a programmed microprocessor 40, and a power source or battery 62. A light-transmissive window 56 at the front end of the housing 55 allows an outgoing light beam 51 to exit and an incoming reflected light 52 to enter. A user aims the reader 10 at a bar code symbol 70 from a position in which the reader 10 is spaced from the symbol, i.e. not touching the symbol or moving across the symbol.
As further depicted in FIG. 2, the optics may include a suitable lens 57 (or multiple lens system) to focus the scanned beam into a scanning spot at an appropriate reference plane. The light source 46, such as a semiconductor laser diode, introduces a light beam into an optical axis of the lens 57, and the beam passes through a partially-silvered mirror 47 and other lenses or beam shaping structures as needed. The beam is reflected from an oscillating mirror 59 which is coupled to a scanning drive motor 60 energized when a trigger 54 is manually pulled. The oscillation of the mirror 59 causes the outgoing beam 51 to scan back and forth in a desired pattern.
A variety of mirror and motor configurations can be used to move the beam in a desired scanning pattern. For example, U.S. Pat. No. 4,251,798 discloses a rotating polygon having a planar mirror at each side, each mirror tracing a scan line across the symbol. U.S. Pat. Nos. 4,387,297 and 4,409,470 both employ a planar mirror which is repetitively and reciprocally driven in alternate circumferential directions about a drive shaft on which the mirror is mounted. U.S. Pat. No. 4,816,660 discloses a multi-mirror construction composed of a generally concave mirror portion and a generally planar mirror portion. The multi-mirror construction is repetitively reciprocally driven in alternative circumferential directions about a drive shaft on which the multi-mirror construction is mounted.
The light 52 reflected back by the symbol 70 passes back through the window 56 for transmission to the detector 58. In the exemplary reader 10 shown in FIG. 2, the reflected light reflects off of mirror 59 and partially-silvered mirror 47 and impinges on the light sensitive detector 58. The detector 58 produces an analog signal proportional to the intensity of the reflected light 52.
The signal processing circuitry includes a digitizer 63 mounted on a printed circuit board 61. The digitizer processes the analog signal from detector 58 to produce a pulse signal where the widths and spacings between the pulses correspond to the widths of the bars and the spacings between the bars. The digitizer serves as an edge detector or wave shaper circuit, and a threshold value set by the digitizer determines what points of the analog signal represent bar edges. The pulse signal from the digitizer 63 is applied to a decoder, typically incorporated in the programmed microprocessor 40 which will also have associated program memory and random access data memory. The microprocessor decoder 40 first determines the pulse widths and spacings of the signal from the digitizer. The decoder then analyzes the widths and spacings to find and decode a legitimate bar code message. This includes analysis to recognize legitimate characters and sequences, as defined by the appropriate code standard. This may also include an initial recognition of the particular standard to which the scanned symbol conforms. This recognition of the standard is typically referred to as autodiscrimination.
To scan the symbol 70, the user aims the bar code reader 10 and operates movable trigger switch 54 to activate the light source 46, the scanning motor 60 and the signal processing circuitry. If the scanning light beam 51 is visible, the operator can see a scan pattern on the surface on which the symbol appears and adjust aiming of the reader 10 accordingly. If the light beam 51 produced by the source 46 is marginally visible, an aiming light may be included. The aiming light, if needed, produces a visible-light spot which may be fixed, or scanned just like the laser beam 51. The user employs this visible light to aim the reader at the symbol before pulling the trigger.
The reader 10 may also function as a portable data collection terminal. If so, the reader 10 would include a keyboard 48 and a display 49, such as described in the previously noted U.S. Pat. No. 4,409,470.
Whilst the known electro-optical systems function highly successfully as readers it is desired to extend their capabilities beyond pure reading implementations.
U.S. Pat. No. 5,577,148 relates to an interactive laser scanner apparatus for displaying an image and receiving input. A video image is displayed at a screen comprising the distal ends of a waveguide bundle. Information can also be received by the apparatus by inputting a signal at the screen which is transmitted by the waveguide bundle and decoded internally.
It is an object of the invention to overcome or mitigate problems associated with known LCD price tagging systems.
In particular it is an object of the invention to provide a system allowing simplified and accelerated updating of prices.
It is a yet a further object of the invention to arrive at improvements to and/or new applications of bar coding systems and other electro-optical readers.